The existing schema need to be supplemented in the area of site information.  There is little allowance for information that is needed for accident reconstruction and safety analysis.  The length, location, and orientation of skid marks are crucial to estimating the speed of a vehicle and the drivers actions at the time of the accident.  The type of any barrier that was struck is essential to studies aimed at evaluating the performance of those barriers.  While accident reports may be available, a mechanism is needed to sort to the ones that involve the specific barrier system of concern.

There is still a lot to be studied in regard to acceptable widths of clear zones and clear areas.  Accident data is key to those studies.  The schema needs to allow the lateral travel of errant vehicles to be documented, as well as the sideslopes of the clear area.  Quality of the clear areas is also an open question, as higher center of gravity vehicles are less likely to perform well on sideslopes that have been considered acceptable for traditional personal vehicles.  The schema needs to allow recording of both sideslopes and vehicle rollover information.

The amount of damage to a barrier system is a key piece of the accident record and also valuable to the maintenance effort to repair that guide rail.

The safety schema should include these and other data about the physical condition of the roadside and the evidence of the crash dynamics.

The TransXML effort should develop draft schema additions for these needs rather than just passing on the suggestion to NHTSA.